1. Field of the Invention
This invention relates to a recording medium capable of reproducing recorded information optically, an optical information reproducing apparatus for reproducing recorded information stored in the recording medium and a seek method using the optical information reproducing apparatus.
2. Description of the Prior Art
Conventionally, there have been such optical disks which are recording media capable of optically reproducing recording data. For example as a rewritable optical disk, there are magnetic optical disks (MO disk, including so-called MD (mini-disk: trade mark)) and phase change type optical disk and the like. As a disk capable of recording only once, write once read many (WOR) disk is available and as a optical disk designed for read only, so-called CD-ROM and the like are currently marketed.
With respect to the aforementioned rewritable optical disks, a number of rewrites is for example about 10.sup.6 times and a number of reproduction is for example about 10.sup.9 times. In optical disks in which recording can be performed only once, a number of recording is only one and a number of reproduction is for example about 10.sup.9 times. In optical disks designed for read only, a number of recording is one and a number of reproduction is theoretically unlimited.
All the aforementioned various optical disks contain a problem relating to copy right. That is, even if for example recorded data is processed with scramble or the like for only users having an appropriate privilege of use in viewpoints of copy right so as to resolve the scramble and reproduce the recorded data, if anyone obtains a means for resolving that scramble, he can pick up the recorded data freely even if he is not a person having an appropriate privilege in terms of copy right.
Further, anyone can pick up recorded data unlimited times from optical disks for use for distribution purpose, for example, optical disks permitted to be for example rented. Thus, it is necessary to collect these optical disks if an appropriate term is passed. That is, although a user having a permission to rent an optical disk can be said to be a proper privileged person for use of that optical disk within a rental period, if that rental period is passed, he loses his privilege for proper use. Thus, that optical disk must be collected. Further, there is a case in which an appropriate optical disk is not desired to be rented for the reason of copy right.